Plant Security Countermeasures
The essay is about veganism and plant eating, but I found the descriptions of plant security countermeasures interesting:
Plants can’t run away from a threat but they can stand their ground. “They are very good at avoiding getting eaten,” said Linda Walling of the University of California, Riverside. “It’s an unusual situation where insects can overcome those defenses.” At the smallest nip to its leaves, specialized cells on the plant’s surface release chemicals to irritate the predator or sticky goo to entrap it. Genes in the plant’s DNA are activated to wage systemwide chemical warfare, the plant’s version of an immune response. We need terpenes, alkaloids, phenolics — let’s move.
“I’m amazed at how fast some of these things happen,” said Consuelo M. De Moraes of Pennsylvania State University. Dr. De Moraes and her colleagues did labeling experiments to clock a plant’s systemic response time and found that, in less than 20 minutes from the moment the caterpillar had begun feeding on its leaves, the plant had plucked carbon from the air and forged defensive compounds from scratch.
Just because we humans can’t hear them doesn’t mean plants don’t howl. Some of the compounds that plants generate in response to insect mastication — their feedback, you might say — are volatile chemicals that serve as cries for help. Such airborne alarm calls have been shown to attract both large predatory insects like dragon flies, which delight in caterpillar meat, and tiny parasitic insects, which can infect a caterpillar and destroy it from within.
Enemies of the plant’s enemies are not the only ones to tune into the emergency broadcast. “Some of these cues, some of these volatiles that are released when a focal plant is damaged,” said Richard Karban of the University of California, Davis, “cause other plants of the same species, or even of another species, to likewise become more resistant to herbivores.”
There’s more in the essay.